JP2010518335A - CVT control system - Google Patents

Abstract

The present invention relates to a simple mechanical device for controlling a multi-regime continuously variable transmission. The transmission in question includes a variator (10) and gearing such as a low regime clutch (C _L ) and a high regime clutch (C _H ). Engagement of the low regime clutch sets the transmission to low regime. Engaging the high regime clutch sets the transmission to high regime. The control system includes a control member (e.g., a lever) that can be moved by a user along the control path from a low ratio end to a high ratio end. The position of the control member determines the variator ratio and the transmission ratio. The system further incorporates a low regime clutch control device that engages the low regime clutch when the control member is between the low end of the path and the low clutch transition point. When the control member is between the low clutch transition point and the high end of the path, the low regime clutch is released. The system also incorporates a high regime clutch control device that releases the high regime clutch when the control member is between the low ratio end of the path and the high clutch transition point. When the control member is between the high clutch transition point and the high ratio end of the path, it engages the high regime clutch. In this way, it is possible to provide a mechanical device that manages both the gear ratio and the clutch change necessary for changing the regime.
[Selection] Figure 3a

Description

  The present invention relates to the control of a multi-regime continuously variable transmission (CVT).

  A CVT typically includes a variator. The term “variator” as used herein has a rotational input and a rotational output and transmits drive from one to the other with a greater drive ratio (ratio of output speed to input speed) than can be changed continuously. Used when referring to the device to be used. Most, but not all, variators include some sort of movable torque transmitting member that is involved in driving transmission, the position of which corresponds to the variator ratio. In the case of a known toroidal race, a rolling traction variator, that is, a roller, functions as a movable torque transmitting member. The roller transmits drive from one toroidal concave race to the other, and its movement is accompanied by a change in roller tilt associated with a change in variator drive ratio. When a force is applied to the movable torque transmitting member, the position is affected, and thus the variator drive ratio is affected. In this way, the variator is controlled.

  CVTs often incorporate an array of clutches (which in some instances may be easily formed as brakes) to select from more than one regime, and the available range of gear ratios To spread. CVT control is typically performed by a high performance electronic controller.

  An object of the present invention is to provide a simple system for controlling the variator ratio and the regime in CVT in a coordinated manner. Specific embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:

FIGS. 1a and 1b are simplified drawings of a variator suitable for use in practicing the present invention, and FIG. 1a is a radial view omitting certain components for the sake of simplicity. On the other hand, FIG. 1b is a perspective view. 2a and 2b are simplified drawings of CVTs suitable for use in practicing the present invention. FIG. 3a is a schematic diagram of a variator control system embodying the present invention. Figures 3b and 3c show the regime control valve of the system in two different states. Figures 3d and 3e show the neutral discharge valve of the system in different states. FIG. 5 is a detailed view of the ratio control valve and related components of the system.

The Variator
1a and 1b show a well-known toroidal lace or rolling traction type variator 10. FIG. The invention has been developed in connection with CVTs using this type of variator and is particularly suitable for that purpose, but in principle other types of variators can also be used.

  The variator 10 includes coaxially mounted input and output races 12, 14, 12 ', 14' and semi-toroidal concave, generally toroidal cavities 16, 16 that house movable torque transmitting members in the form of rollers 18, 18 '. ′ And adjacent surfaces 6 and 8. The variator typically has two or three of the above rollers spaced circumferentially spaced around each cavity 16, 16 '. Each roller 18 rides on surfaces 6 and 8 of the respective race 12 and 14 and thus serves to transmit power from one to the other. The roller 18 can move back and forth around the common axis 20 of the races 12 and 14 along the circumferential direction.

  Laura can also precess. That is, the direction of the roller axis can be changed while changing the inclination of the roller axis with respect to the disk axis. In the illustrated embodiment, the above motion is provided by rotatably mounting the roller 18 to a support member 22 connected by a stem 24 to a piston 26 of an actuator 28. A straight line 19 from the center of the piston 26 to the center of the roller 18 constitutes a precession axis that can change the direction of the entire assembly. The roller precession causes a change in the radius of the path following the roller marks on the races 12 and 14, and thus a change in the drive ratio of the variator.

  It should be noted here that in the present embodiment, the precession axis 19 is not exactly in a plane perpendicular to the common axis 20, but instead is inclined to the plane. The tilt angle is the sign CA in the drawing and is known as the “caster angle”. As the roller moves back and forth, the roller follows an annular path about the common axis 20. Furthermore, the action of the races 12, 14 on the rollers causes the roller axis to tilt so that it intersects the common axis 20, creating a steering moment that tends to maintain the rollers. The caster angle allows the above-mentioned axis crossings to be maintained regardless of the back-and-forth movement of the roller along the annular path. As the roller moves along its path, the roller is also steered by the action of the race and precesses to maintain the crossing of the axes. As a result, the position of the roller along the path corresponds to a predetermined roller slope and thus a predetermined variator drive ratio.

  The actuator 28 receives the pressure of the opposing hydraulic fluid via the supply pipes S1 and S2. In this way, the force created by the actuator 28 drives the rollers around the common axis 20 along an annular path, and in equilibrium, balance is maintained by the forces acting on the rollers by the races 12,14. The force exerted by the race is proportional to the sum of the externally applied torque to the variator race. This sum is-the sum of the variator input torque and the variator output torque-is the net torque that should react against the variator mounting, and is called reaction torque.

The transmission
2a and 2b show one embodiment of two regime transmissions suitable for implementing the present invention in a highly stylized manner. Many different types of multiple regime CVTs are known in the art, many of which can be used in the practice of the present invention. Thus, although the structure of the transmission will be described in detail, these should not be taken as limiting the scope of the present invention.

  In the drawings, a rotational power source manufactured as an internal combustion engine in this embodiment is indicated by ENG and drives input races 12 and 12 ′ of the variator 10. The transmission is a planetary “shunt” gear train having a planet carrier PC coupled to the engine via a gear train G and a sun gear S coupled to the variator output races 14, 14 ′ of the variator. E is provided. In other transmissions, a coaxial output drawn from the variator output is often used, but in the illustrated embodiment, a chain CHA is interposed in the connection. The planetary gear P attached to the carrier PC drives the annular output gear A and meshes with the sun gear S. The driven wheel is indicated by W.

The transmission shown is operable in high and low regimes that are engageable via high and low regime clutches C _H , C _L. When low regime clutch C _L is engaged, the output gear A of the shunt E is coupled to the wheel. Note that the speed of the output gear A is determined by the speed of both the planet carrier PC and the sun gear S. The speed of the carrier PC has various engine speeds, and the speed of the sun gear S varies depending on the variator ratio.

  At a specific variator ratio (“gear-neutral ratio”), these speeds cancel each other, so output gear A is stationary. In such a state, the transmission effectively provides continuously variable deceleration, and the output of the transmission does not fluctuate despite being mechanically connected to the running engine. This state is called “geared neutral”. By simply adjusting the variator ratio, it is possible to obtain various gear ratios on both sides of the gear neutral-providing both forward and reverse travel for the vehicle-while the transmission is in low regime.

The engagement of the release of the engagement of low regime clutch C _L and the high regime clutch C _H, by setting the transmission into high regime, can be used more extensive forward ratios. In such a state, only the components seen in FIG. 2b are in the output flow path between the engine and the wheels. Variator output is connected through an output take-up CHA, high regime clutch C _H is connected to the wheels W. Gear neutral is not available in the high regime.

  The relationship between the variator ratio and the transmission ratio (ratio of output transmission speed to input transmission speed) differs between the two regimes. In the high regime, increasing the variator ratio increases the total transmission ratio. In the low regime, increasing the variator ratio decreases the total transmission ratio. This must be taken into account when controlling the variator.

  For a certain variator ratio ("synchronization ratio") where the variator ratio is in one extreme range, the gear ratio is selected by the transmission so that both the high and low regimes have the same transmission ratio. Since there is no change in the ratio caused by the overall transmission during the transition period, the regime can be changed smoothly with the synchronization ratio.

User Operable Controls
Hereinafter, a control system embodying the present invention will be described with reference to FIG. The control system is useful for coordinated control of (a) the hydraulic control pressure on the variator, and thus the variator ratio, and (b) the hydraulic control pressure on the high and low regime clutches C _H , C _L.

  The main control device of the driver is formed as a handle lever in this embodiment, and may take other forms, but is formed by the user operation unit 50 which will be described below. The handle lever 50 is movable back and forth about a first axis 52 orthogonal to the plane of the page of FIG. 3a and laterally about a second axis 54 in the plane of the page. The terms “fore-and-aft” and “lateral” are used for convenience in relation to lever movement, but do not necessarily reflect the lever travel relative to the vehicle.

  The movement of the handle lever 50 is constrained by the engagement of the guide plate 58 with the forming slot 56. The slots extend in the lateral direction from the low regime zone to the high regime zone and the first longitudinal stretch portion of the low regime zone 60, the second longitudinal stretch portion of the high regime zone 62, and the gate 64 parts. Further, there is a side branch called a neutral zone 66 in the middle along the low regime region.

By moving the handle lever 50, the driver controls both the variator 10 and the clutches C _H and C _L. In the present embodiment, the driver can obtain an arbitrary ratio within a shift range including gear neutral by simply moving the handle lever 50.

  However, the system also includes a user operable torque release control device, which in this embodiment is configured as a torque release pedal 68. Again, this control device may take other forms, such as a manually operable lever. The function of the torque release pedal 68 is similar to that of a clutch pedal in an automobile. By operating the pedal, the user can effectively decouple the output of the transmission from the engine and move the engine with inertia. A method for realizing this will be described below.

Variator Ratio Control
The variator ratio—and the drive ratio provided by the overall transmission—are adjusted by moving the handle lever 50 back and forth. By moving the hand lever 50 to the farthest rear position, it selects the variator highest effective ratio, the effect of the shunt gearing described above (shunt gearing), and low regime clutch C _L is engaged In the state, the entire transmission selects the maximum effective reverse gear. Therefore, the car travels backward.

  As the handle lever 50 is advanced, the lever reduces the variator ratio and hence the overall reverse gear ratio of the transmission. When the handle lever 50 reaches the neutral zone 66 (the lever position shown in FIG. 3a), the transmission is set to gear neutral-that is, its output does not change and the car remains intact. By further advancing the handle lever 50 along the low regime zone 60, the variator ratio continues to decrease, and when the handle lever 50 reaches the gate 64, the variator is at its minimum ratio (with the aforementioned synchronization ratio). The transmission will provide an increased forward drive ratio until the transmission is at the highest forward drive ratio available in the low regime.

As the handle lever 50 is advanced further, the lever must move across the gate 64. This causes the transmission to undergo a regime change from low to high, as will be described below. Next, when the lever is advanced along the high regime zone 62, the lever increases the variator ratio, the high regime clutch C _H is immediately engaged and the low regime clutch C _L is engaged. Until the handle lever 50 reaches the maximum forward gear at the forward end 72 of its stroke, the drive ratio of the entire transmission is similarly increased.

  The mechanism that the handle lever 50 controls the variator 10 is a hydraulic mechanical type, and (a) a conversion mechanism that converts the position of the handle lever 50 into a position signal that displays the required variator ratio, and (b) true A comparator to help produce a corresponding correction signal, and (c) receive the correction signal and respond to it with a corrective force in response to the desired variator ratio. In addition, it includes a ratio controller that prompts the user to select a desired ratio. The comparator and control device together control the variator in a closed loop, causing the variator to select the value determined by the conversion mechanism. The physical configuration of these three functional units will be sequentially described below.

  The conversion mechanism includes a cam 78 and a follower 80. When the handle lever 50 moves back and forth, the cam 78 rotates about the first axis 52, so that the follower 80 moves. The position of the follower 80 produces a mechanical signal indicating the desired variator ratio.

  Since the relationship between the handle lever position and the desired variator ratio is different between the two regimes as described above, a conversion mechanism is required. In the low regime, the variator ratio decreases as the handle lever 50 is advanced. In the high regime, the variator ratio increases when the handle lever 50 is advanced. In FIG. 3a, the handle lever 50 is shown in phantom lines at four positions AD.

  Lever positions A and D display the maximum reverse transmission ratio (in low regime) and the maximum forward transmission ratio (in high regime), respectively. Both positions require the variator to be at its maximum ratio, so the corresponding cam radii a and d are the same. In the embodiment shown, these are the minimum cam radii. The lever position C corresponds to gear neutral and the cam radius c is selected to give the gear neutral variator ratio. Lever position B is obtained when the handle lever 50 is at the gate and the variator is at the sync ratio-i.e. its lowest effective value. The cam radius b is selected to provide this, which in this embodiment is the maximum cam radius.

  The comparator is a simple mechanical device in this embodiment, and once again, those skilled in the art will be able to devise many other devices suitable for the purpose. This uses a comparator bar 82 having a first end connected to the follower 80 and a second end connected to a roller of the variator 10 (shown schematically at 84 in FIG. 3). In the illustrated embodiment, an elbow lever 86 having a fulcrum at 88 is interposed between the follower 80 and the comparator bar. The follower 80 is supported by one end of this lever. The other end is connected to the comparator bar 82 by a wire linkage 90. A spring 92 serves to hold the wire linkage 90 in tension and to press the follower 80 against the cam 78. The midpoint 94 of the comparator bar is connected to a ratio control device which in this embodiment takes the form of a ratio control valve 96.

  FIG. 4 shows a ratio control valve 96 with a spool connected via a rod 98 to a midpoint 94 of the comparator bar. The inlet port 100 of the ratio control valve 96 is connected to the pump 102, and pressurized fluid is supplied to the inlet port. A discharge port 104 leads to an oil sump 106 of the transmission. Supply ports 108 and 110 lead to the respective pipes S1 and S2 and thus to the opposite side of the piston 26 which controls the rollers of the variator (in this regard, see FIG. 1 again). The valve has a central position where all ports are closed, a pipe S1 is connected to the pump 102, an S1 supply position where oil in the pipe S2 is discharged to the sump 106, and a supply pipe S2 is pressurized from the pump 102. On the other hand, it has an S2 supply position where oil in the pipe S1 is discharged to the oil sump 106. The valve response is proportional. That is, the opening degree of the port continuously changes depending on the spool position.

  Consider what happens when there is a discrepancy between (a) the ratio commanded by the user through the handle lever 50 and the conversion mechanism and (b) the true variator ratio. For illustrative purposes, the handle lever 50 has moved and, as you can see, the first end of the comparator bar 82 has moved to the right, resulting in a discrepancy (the ratio is slightly different from the required value, so the same Assuming that Assuming that the second end of the comparator bar 82 does not move, the midpoint of the bar should also move to the right and adjust the ratio control valve 96. In this way, the pressure in the pipes S1 and S2 is adjusted to tend to bring the variator ratio to a desired value. As a result, the desired ratio is obtained and the spool of the ratio control valve 96 returns to the intermediate position. Until the second end of the comparator bar moves to the left. The effect is to provide closed loop control of the variator ratio.

Regime control
The variator control system must manage the operation of the clutches C _H and C _L in the transmission. In particular,
i. While the hand lever 50 is in the low regime zone 60, the user while not release the transmission, low regime clutch C _L is engaged, the engagement release of the high regime clutch C _H Done;
ii. While the hand lever 50 is in the high regime zone 62, the user while not release the transmission, the high regime clutch C _H is engaged, the engagement release of the low regime clutch C _L Done;
iii. The transition from low-regime clutch engagement to high-regime clutch engagement or vice versa must be managed when the transmission passes the sync ratio.

  In the embodiment illustrated in FIG. 3a, there is a point in the stroke of the handle lever 50 where attention is directed to the low clutch transition point (LCTP), after which the low The state of the clutch changes-when the lever moves forward, it changes from engagement to disengagement, and when the lever moves backward, it changes from disengagement to engagement. In addition, the handle lever has a high clutch transition point (HCTP) that changes the state of the high clutch when it passes through. -When the lever moves forward, it changes from disengagement to engagement, and when the lever retracts. Change from engagement to disengagement. Both LCTP and HCTP are in the handle lever position corresponding to gear neutral. These can occur in principle in synchronism so that the states of the two clutches change at the same time, but in this embodiment, the LCTP is in the lever position advanced from the HCTP. Therefore, the approaching clutch is engaged before the previous clutch is released. This is possible because regime changes occur at the sync ratio.

  In the illustrated embodiment, the regime change occurs when the handle lever 50 crosses the gate 64. As a result, the driver will notice that a regime change is taking place, which may be desirable. The lateral position of the handle lever 50 controls the clutch via the high and low clutch valves 112, 114, to which the spool is coupled to the handle lever 50 and moves with its lateral movement.

High and low clutch valves 112, 114, respectively, associated clutch _C H, clutch supply port ₁₁₆ leading to the _{C L} H, 116 _L, clutch exhaust port ₁₁₈ communicating with the sump 106 H, 118 _L, and the pressure There are input ports 120 _H and 120 _L that are connected to a pump that supplies the hydraulic fluid (which may be the same pump 102 used to supply the variator control pressure).

When the transmission is in high regime, the handle lever 50 is in the high regime zone 62 and thus in the lateral position seen in FIG. 3b. The low regime clutch C _L is disengaged via the low clutch valve 114 and the high regime clutch C _H is pressurized via the high clutch valve 112, thus the high regime clutch C _H Only engage. When the transmission is in the low regime, the handle lever 50 is in the low regime zone 60 and thus in the lateral position seen in FIG. 3c. The high regime clutch is broken. The low regime clutch is pressurized and thus engaged. The lateral movement of the handle lever 50 required to change from one of these states to the other can only take place when the lever is at the gate 64 and therefore the transmission is in sync ratio.

Torque release
In a conventional vehicle equipped with a manual transmission, a clutch pedal that is hydraulically coupled to a clutch that connects the engine to the transmission is prepared by the driver, and the clutch pedal is pressed to connect to the engine. It is possible to drive the car with inertia. Torque release pedal 68 provides a somewhat similar function but operates in different ways.

In the transmission of the type illustrated in FIG. 2, there are in principle two methods for detaching the wheels from the engine in an operable manner. The first method is to release both clutches C _H and C _L. The second method is to cut off the pressure of the supply pipes S1 and S2. When these pressures are released, the piston 26 cannot apply force to the variator roller 18 (again, see FIG. 1 in this regard). Therefore, the variator 10 cannot maintain the reaction torque at that time. In this state, the variator automatically selects a ratio determined by the relative speeds of the engine and wheels. Although the wheels are not physically disconnected from the engine, the wheels can travel with inertia because the variator cannot apply torque to the wheels. This mode of operation is referred to as “reaction torque release”.

FIG. 3 a shows a reaction torque release valve 124, which is a proportional valve that is controlled by a user through mechanical coupling with a torque release control device 68. The reaction torque release valve 124 operates in conjunction with the interlock valve 126, the spool of the interlocking valve, as indicated by the arrow 128, the control pressure is applied to be captured from the low regime clutch C _L.

  When the transmission is in the low regime, the interlock valve 126 is thus maintained in a state where the ports a and b of the reaction torque release valve 124 are connected. The ports c and d of the reaction torque release valve 124 are connected to supply pipes S1 and S2, respectively. While the transmission is in the low regime, the reaction torque release valve 124 is opened by the operation of the torque release pedal 68 by the driver, and a path is provided between the pressure supply pipes S1 and S2. When the valve is fully opened, the pressure in the pipes S1, S2 is at least substantially equal, providing a reaction torque release function. If a certain pressure difference is maintained, a certain amount of “creep torque” may be applied. Further, since the reaction torque release valve 124 is a proportional valve, the driver can set the wheel torque at an intermediate level by pushing down the torque release pedal 68 slightly, as in the conventional clutch control device.

  A driver familiar with the manual transmission will probably stop the car by depressing the torque release pedal 68 and applying the brakes. This does not cause any difficulty if the transmission is in low regime. When the car stops, the transmission is in gear neutral. However, if the car is in the high regime, the high regime is not in gear neutral, so the driver cannot stop the vehicle even if the reaction torque of the variator is released. In other words, the variator will reach the ratio limit before the car stops.

In the high regime, the interlock valve 126 disconnects the ports a and b in the reaction torque release valve 124 and disables the valve. Therefore, reaction torque release is not available in the high regime. Instead, torque is released by the control of the high regime clutch C _H. It should be noted in this regard that the pressure output from the high clutch valve 112 is not directly connected to the high regime clutch, but instead is controlled by itself through a mechanical connection with the torque release pedal 68. The high clutch control valve 130 guides the pedal and depresses the pedal so that the oil is discharged into the sump by the high regime clutch. Therefore, by depressing the pedal, the user releases the high regime clutch C _H, so disconnect the engine from the wheels.

Geared Neutral
The user does not necessarily have to use the torque release pedal to stop the car. Instead, they simply use the handle lever 50 to set the transmission to gear neutral, and in this embodiment, move the handle lever laterally into the neutral zone 66. Thus, it may be straight and forward (positive way). However, if the lever position determined by the neutral zone 66 is slightly different from the position necessary to obtain gear neutral (for example, due to minor misalignment), in principle, a large torque will be inadvertently applied to the wheel. May lead to results.

  To avoid such problems, the illustrated system is configured to release the variator reaction torque when moving the handle lever 50 to the neutral zone 66. This is accomplished using a neutral discharge valve 132 with each port connected to the supply piping S1, S2. The handle lever 50 is in one of its “driving” zones—high regime zone 62, low regime zone 60, and gate 64—as supported by the discussion of FIGS. 3a, 3d and 3e. Meanwhile, the neutral discharge valve 132 closes the port and has no effect on the operation of the transmission. When the handle lever 50 is moved to the neutral zone 66, the port is opened to empty the supply pipes S1 and S2 and release the reaction torque of the variator.

Claims (15)

A control system for a continuously variable transmission including a variator, a low regime clutch that selectively engages a low transmission regime, and a high regime clutch that selectively engages a high transmission regime. There,
A control member that can be moved by a user from a low specific end to a high specific end along the control path, the position of which controls the variator ratio and the transmission ratio, and the control member is connected to the low ratio end of the path and the low clutch transition point. A low regime clutch control device that engages a low regime clutch when in between and releases the low regime clutch when the control member is between the low clutch transition point and the high end of its path And when the control member is between the low ratio end of the path and the high clutch transition point, the high regime clutch is released, and the control member is between the high clutch transition point and the high ratio end of the path. A high regime clutch control device that sometimes engages the high regime clutch.   The system of claim 1, wherein the low clutch transition point and the high clutch transition point are both at locations in the control path corresponding to a synchronous variator ratio.   The system of claim 1, wherein the high clutch transition point is closer to the low ratio end of the control path than the low clutch transition point so that both clutches are engaged when the control member is between the transition points.   The system of claim 1, wherein the high clutch transition point and the low clutch transition point are in the same position.   5. A system according to any one of the preceding claims, including a conversion mechanism for converting the position of the control member into a machine signal indicating the required variator ratio.   The system of claim 5, wherein the conversion mechanism includes a cam surface and a follower, the position of the follower forming a mechanical signal.   The shape of the cam surface is such that when the control member moves from the low specific end of the control path to the high specific end, the follower is displaced by the cam surface first in one direction and then in the opposite direction. The system according to claim 6.   8. The system of claim 7, wherein reversal of the follower movement direction occurs when the follower is in a position corresponding to a variator gear-neutral ratio.   The machine signal indicating the requested variator ratio is also connected to a comparator that receives the machine signal indicating the current variator ratio and provides a machine signal indicating an error in the variator ratio. 9. The system according to any one of items 8.   The comparator includes a bar coupled to the follower at the first location and to the coupling with the variator roller at the second location, and the mechanical signal is intermediate between the first location and the second location via the coupling. A system according to claim 9 when dependent on claim 6, provided to the bar.   11. A system according to claim 9 or 10, wherein the comparator controls a ratio control valve arranged to apply hydraulic control pressure to the variator.   12. A system according to any one of the preceding claims, wherein the control member is movable in a first direction that changes the variator ratio and a second direction that changes the state of the high and low regime clutches. The control path is
(A) a first portion extending along the first direction from a low specific end in the stroke of the control member;
(B) having a second part extending along the second direction, and (c) a third part extending along the first direction,
13. The control member of claim 12, wherein the control member moves along the second portion to change the state of the valve as the control member moves from a low to a high ratio end of the path, thereby performing a regime change. System.   Including at least one valve operably connected to the control member such that the state of the valve can be changed by moving the control member along a second direction, the valve relative to the at least one clutch; The system according to claim 12 or 13, which controls the hydraulic pressure. Arranged between a pair of semi-toroidal concave races, including a control member that can be moved by the user to set the required gear ratio, a conversion mechanism comprising a cam surface and a follower movable relative to the cam surface by the control member And a variator including at least one roller for transmitting drive from one to the other, and a continuously variable transmission,
A roller is movable and a hydraulic actuator is operatively connected to the roller to control the position of the roller to adjust the ratio of the speed of one race to the speed of the other race, and a mechanical comparator (A) a first input element operably connected to the roller and moving in synchronism with the roller; (b) a second input element operably connected to the follower and moving in synchronism with the follower; And (c) a ratio control valve comprising an output element operably connected to the ratio control valve, wherein the position of the output element is determined by the relative position of the two input elements and controls the hydraulic pressure applied to the hydraulic actuator. Is a continuously variable transmission that provides the required gear ratio by moving the roller with hydraulic pressure applied to the roller based on the discrepancy between the roller position and the required gear ratio.

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